docs: def _regressor_names(con_name, hrf_model, fir_delays=None):
      """ Returns a list of regressor names, computed from con-name and hrf type
  
      Parameters
      ----------
      con_name: string
          identifier of the condition
  
      hrf_model: string or None,
         hrf model chosen
  
      fir_delays: 1D array_like, optional,
          Delays used in case of an FIR model
  
      Returns
      -------
      names: list of strings,
          regressor names
      """
      if hrf_model in ['glover', 'spm', None]:
          return [con_name]
      elif hrf_model in ["glover + derivative", 'spm + derivative']:
          return [con_name, con_name + "_derivative"]
      elif hrf_model in ['spm + derivative + dispersion',
                         'glover + derivative + dispersion']:
          return [con_name, con_name + "_derivative", con_name + "_dispersion"]
      elif hrf_model == 'fir':
          return [con_name + "_delay_%d" % i for i in fir_delays]